Automotive Science and Engineering

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The objective of developing kinetic energy recovery systems for vehicles is to repurpose energy otherwise dissipated during braking. Brake energy recovery and storage are achieved through two broad methods: electrical and mechanical, contingent on the energy storage type and the traction system's operational approach. Utilizing a rotating flywheel emerges as a practical, cost-effective, safe, and environmentally friendly means of storing energy, offering an extended service life. This study, synthesizing insights from various theories, aims to devise a prototype brake energy recovery system compatible with Samand car, employing the flywheel tank. Additionally, considerations for the power transmission system and clutch involve designing their type and dimensions, taking many factors into account for the selection. The initial design undergoes simulation and evaluation using MATLAB_SIMULINK and the ADVISOR plugin. The investigation delves into the influence of various design parameters on the efficiency of the system. Subsequently, attempts are undertaken to clarify the factors contributing to varied outcomes. The simulation results indicate a notable decrease in fuel consumption and emissions for a Samand car during urban driving cycles characterized by frequent braking. This improvement is realized through the utilization of a steel flywheel with an incomplete cone geometry and a specified radius. Suggestions are put forth for refining the controller to potentially enhance reductions in fuel consumption and pollution.

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The global transition towards renewable energy necessitates efficient energy storage solutions to address the intermittency of renewable sources. Lithium-ion batteries (LIBs), widely utilized in electric vehicles (EVs) for their high energy density and efficiency, yet their performance at low temperatures remains a challenge. This study investigates the influence of electrolyte solvent composition on LIB performance under low-temperature conditions. Three electrolytes were studied: a standard electrolyte (STDE) comprising 1 M LiPF₆ in ethylene carbonate (EC) and diethyl carbonate (DEC), a low-temperature electrolyte (LTE) consisting of 1 M LiPF₆ in EC, ethyl methyl carbonate (EMC), and ethyl acetate (EA), and a long-cycle-life electrolyte (LCLE) containing 1 M LiPF₆ in EC/EMC. The EIS results revealed significant differences in resistance values among the electrolytes at varying temperatures. Specifically, at 0 °C, the STDE exhibited a charge transfer resistance (R_ct) of 1055.3 Ω and a solid electrolyte interface resistance (R_SEI) of 803.4 Ω, whereas the LTE showed a substantially lower R_ct of 507.4 Ω and R_SEI of 64.2 Ω, indicating superior low-temperature performance. Similarly, at -20 °C, the R_ct values for STDE, LTE, and LCLE were 8878.6 Ω, 854.2 Ω, and 15622 Ω, respectively, with corresponding R_SEI values of 172.1 Ω, 92.4 Ω, and 2364 Ω. Notably, the addition of EA in the LTE formulation contributed to enhanced low-temperature performance, likely by lowering the overall viscosity of the electrolyte mixture and improving ionic mobility. This study demonstrates the critical role of solvent composition, particularly EA, in optimizing LIB performance for cold climate applications.
 

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High-entropy oxides (HEOs) are single-phase crystal structures composed of multiple metal elements that provide great potential for energy storage applications due to the synergistic effect of various metal species. They are considered effective anode materials for high-performance lithium-ion batteries (LIBs) because of their structural stability, high electronic conductivity, and ability to create anode materials with novel structures using several elemental compounds. Because the effects of different types of electrochemically active elements on the properties of anode materials are unknown, it is necessary to develop HEOs and investigate their properties. Herein, to explore the electrochemical properties of HEOs by changing the content of cations with various mechanisms for storing lithium, we prepared three samples of HEOs with spinel structure using the solid-state method, one of which is equimolar ((MgNiTiFeZn)_0.6O₄) and two numbers are near-equimolar ((Mg_0.6Ni_0.6Ti_0.3Fe_0.9Zn_0.6)O₄ and (Mg_0.6Ni_0.6Ti_0.3Zn_0.9Fe_0.6)O₄)). For structural properties determination, X-ray diffraction analysis was used. The results confirmed the formation of three single-phase high-entropy oxides.
Electrochemical tests indicated the structural stability of three compounds of high entropy oxides, and the composition of (MgNiTiFeZn)_0.6O₄, relative to the others, has better rate capability (163 mAhg⁻¹ at 1000 mAg^–1) and higher discharge capacity (220 mAhg⁻¹ at 200 mAg^–1) after 200 cycles.

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In the automobile sector, stainless steel and resistance spot welding (RSW) are often used. In this work, RSW was used to join five samples of 316L stainless steel joints at currents of 15, 20, 25, 30, and 35 kA while the heat input parameters varied. The welded joints' microstructure, hardness, and mechanical properties were examined and evaluated. The base metal, heat-affected zone (HAZ), and weld areas' microstructures were all examined using optical microscopy. The mechanical characteristics of the joints were assessed using room-temperature tensile-shear testing and hardness testing. The microstructure findings revealed ferrite in many weld regions and an austenitic structure overall. In the samples with welding currents of 15, 20, 25, 30, and 35 kA, the average hardness of the weld zone was 329, 258, 251, 238, and 235 Vickers, in that order. The hardness of the weld zone exhibited an inverse connection with the welding current, as an increase in welding current resulted in a drop in the resistance spot welded area's hardness. Furthermore, when heat input increased, the hardness of the HAZ reduced and increased relative to the 316L steel. The joint strength of the RSW increased with increasing welding current, as demonstrated by the tensile-shear test results for all five welded samples with varying currents. As a result, the samples with 30 and 35 kA currents failed at the weld with a force greater than 3 kN, while the other samples with lower welding currents had a failure force of less than 2 kN.
 

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A novel liquid cooling system for pouch-type lithium-ion batteries (LIBs) is proposed by focousing on uniform temperatue disturbution and effective heat dissipation. The system utilizes a michrochannel cold plate with an innovative coolant disturbution design. This study proposes a novel microchannel disturbution path design with each microchannel dimensioning 1 mm² and embeded in the battery's ciritical region to enhance the thermal contact among the LIB and the microchannels. This study aims to simulate and evaluate the performance of cooling system under varius Iranian environmental conditions (Tehran, Shiraz, Isfahan, and Bandar Abbas) and operational parametrs (channel pattern, flow rate) to achieve optimal battery temperature and reduce energy consumption.

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A bus experiences various loads during operation, stressing its structural components and causing noise, vibrations, and strains. To withstand these stresses, components must have sufficient stiffness, strength, and fatigue properties. In this study, the CAD model of a bus was created in SolidWorks and meshed using HyperMesh. A modal analysis conducted in HyperMesh verified the model's integrity, welding joint accuracy, and suitability for further analysis. A HyperMesh solver performed bending and torsional analyses. The torsional and bending stiffness of the bus body was calculated based on these results. Previous research primarily focused on stress and displacement, neglecting torsional and bending stiffness analysis for three-axle buses. This study addresses this gap, providing industry engineers with insights into acceptable torsional and bending stiffness for intercity buses. This knowledge supports the design of buses with adequate braking and turning capabilities. Additionally, the research contributes to bus body optimization efforts. In subsequent studies, scientists can experiment with various materials and models of various bus structure beam profiles.

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The impact of a supercooled droplet on a surface is a primary challenge of many industrial and aeronautical processes. However, in some cases, such as frost formation on vehicle windshields or wind turbine blades, the supercooled droplet collision does not occur in stagnant air. In this study, for the first time, the effects of the air transverse flow (ATF) on the thermal-fluid behavior of a supercooled droplet were investigated numerically. Also, different patterns of a superhydrophobic pillared surface were used in 24 three-dimensional simulations in ANSYS Fluent software. The volume of fluid method is chosen for the simulation of the multiphase flow. The freezing model is improved by the supercooling temperature consideration method. The results show that the ATF velocity reduces the separation time exponentially and helps the droplet bounce from the surface before freezing inception. However, the excessive increase in ATF velocity has the opposite effect and may prevent the droplet from detaching the surface due to notable drag. The best value of the ATF velocity is obtained to be 8 m/s , which reduces the separation time exponentially from 16.3 ms  to 12.5 ms  for a cold surface with a simple pillar pattern. The separation time is entirely affected by the simulation conditions and varies from 11.85 ms  to 29.2 ms . The maximum spreading factor, despite the separation time, is seriously influenced by the void fraction percentage of different pillared surfaces and varies from 1.53 to 1.69.

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Adhesively bonded joints are a highly effective method for achieving lightweight structural designs, yet assessing their long-term durability remains a significant challenge. Creep, a time-dependent effect caused by sustained mechanical loads, can result in viscous strain within adhesive materials, potentially leading to crack formation in bonded structures over extended periods. This study investigates the creep behavior of adhesive joints under sustained tensile loads, focusing on the effects of adhesive layer thickness and the presence of adhesive fillets. Creep tests conducted over 48 hours revealed that higher load levels result in greater strain accumulation, with thicker adhesive layers showing increased susceptibility to deformation. Additionally, joints with adhesive fillets demonstrated lower creep strain, indicating enhanced resistance to sustained loads. These findings emphasize the importance of adhesive layer thickness and fillet design in optimizing the long-term performance and durability of bonded joints, offering valuable insights for applications where creep resistance is critical for joint reliability and service life.

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This study investigates the influence of nozzle hole diameter (NHD) variations on spray dynamics, combustion efficiency, and emissions in a Reactivity-Controlled Compression Ignition (RCCI) engine using Computational Fluid Dynamics (CFD) simulations with the CONVERGE software. The study systematically examines NHDs ranging from 130 µm to 175 µm and evaluates their impact on key parameters such as injection pressure, droplet formation, Sauter Mean Diameter (SMD), and evaporation rates. The results demonstrate that reducing NHD to 130 µm significantly enhances fuel atomization by reducing SMD to 15.49 µm and increasing droplet number by 24%, which in turn accelerates evaporation and improves fuel-air mixing. These effects shorten ignition delays, accelerate combustion, and increase peak cylinder pressures and temperatures. Optimal NHDs (150–160 µm) achieve the highest combustion efficiency (92.04%) and gross indicated efficiency (38.58%). However, further reduction in NHD below this range causes premature ignition, energy dissipation, and higher NOx emissions (10.08 g/kWh) due to elevated combustion temperatures. Conversely, when the NHD increases to 175 µm, the larger droplets formed result in prolonged ignition delays, slower combustion, and lower peak pressures. These effects negatively impact combustion efficiency and promote incomplete combustion, leading to higher HC (15.27 gr/kWh) and CO (4.22 gr/kWh) emissions. Larger NHDs, however, lower NOx emissions to 2.66 gr/kWh due to reduced peak temperatures. This study clearly identifies an optimal NHD range (150–160 µm) that effectively balances droplet size, evaporation rate, combustion timing, and emission reduction, thereby enhancing both engine performance and environmental sustainability.

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One of the most important aspects of designing passenger cars is the engine cooling. This process would significantly affect the vehicle performance. This study has been conducted both theoretically and experimentally to reveal the influences of different involved parameters of cooling. The current research is implemented in order to examine the effects of 2-speed radiator fan utilization rather than the 1-speed type. For this aim, the new modified fan is considered and the experimental data are obtained to compare the results with those of the old one. Additionally, the effects of parameters such as ECU strategy, radiator fin density as well as the radiator plate geometrical properties are considered in the analysis. As a prominent result, the experimental results show a substantial effect of considering 2-speed radiator fan and choosing a better strategy for ECU on the cooling performance in the vehicle. The experimental results show that employing 2-speed fan instead of single-speed and 900 fin/m fin density instead of 780 fin/m decreases coolant outlet temperature of radiator by 6.1% and 7.1% in the same condition, respectively.
 

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This study explored the impact of Super P on the specific capacity of MXene-based rechargeable Li-O₂ batteries. It was found that increasing the Super P ratio from 10% to 30% significantly improved the specific discharge capacity of the lithium-oxygen battery, rising from 396 mAh g⁻¹ to 1116 mAh g⁻¹ during the first cycle at a current density of 100 mA g⁻¹. To characterize the structure of the synthesized MXene, analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy were utilized. The electrochemical performance of the fabricated electrodes was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The findings indicate that the synergistic interaction between MXene and Super P contributes to the enhanced capacity of the fabricated cell.

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This paper presents an efficient dynamic programming method in order to examine the problem of optimal power management of hybrid electric vehicle (HEV) powertrains and compares its performance with a rule-based method. Since dynamic programming is a trajectory based optimization algorithm and provides a globally optimal solution, it can be used as a benchmark for assessment of other control strategies. However, a major limitation of this method is its extreme computational load which is known as the curse of dimensionality. The computation time and the memory requirements increase exponentially with the increase of states and inputs. In this paper, a novel approach is used to decrease the total computation load and shows how this improvement can provide more accurate results.
 

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The engine mounting bracket is connected to the engine on one side and to the car body on the other side. The engine mounting bracket should be designed in such a way to prevent the transmission of vibrations from the body to the engine and vice versa. In addition, one of the tasks of the engine mounting bracket is to bear the weight of the engine and the dynamic and vibrational loads caused by the movement of the car on the road. The engine mounting bracket are generally designed in such a way that they have sufficient fatigue life in a defined range of cyclic forces and fail in the range of high forces caused by an accident in order to minimize the level of damage to the vehicle and passengers. This research will investigate the effect of manufacturing parameters on the fatigue behavior of the aluminum engine mounting bracket. High-cycle fatigue test was taken from the prototypes and based on the results of this test, the prototype was considered unsafe.  Therefore, in order to improve the produced part, by removing the factors that cause weakness in the part and strengthening the area in front of the engine mounting bracket, the secondary sample of the engine mounting bracket was produced, but due to the high costs of re-fatigue testing, radiographic test was done of the reinforced areas before testing. Then, fatigue test was taken from the secondary sample. The test results of the modified sample were within the acceptable range.

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The transition from traditional internal combustion engine vehicles to electric vehicles is in progress. With their high energy density, low self-discharge rates, long cycle life, and absence of memory effects, lithium-ion batteries have become the primary power source for alternative vehicles. Throughout the battery's lifespan, its performance or health gradually deteriorates due to irreversible physical and chemical changes. Depending on the specific aging mechanisms, a battery may lose capacity or face increased internal resistance. Growing awareness of the importance of environmental protection and the potential implications associated with products and services has spurred interest in developing methods to better understand and address these impacts. Life cycle assessment is a method used to examine the environmental effects associated with all stages of product production. This study compares the operational conditions of an electric vehicle equipped with both new and old battery packs. The performance difference indicates that the vehicle with the aged battery has 17% less capacity, operates over 20% weaker in range, and its ohmic resistance increases by up to 150%. From a well-to-wheel perspective, using an electric vehicle with an old battery could result in a 2% increase in carbon dioxide emissions, reaching 56.638 g CO₂ equivalent per kilometer.

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One of the main challenges in designing a vehicle's cooling system, particularly the radiator, is not considering the non-uniform airflow distribution in the radiator's characteristic performance graphs. In this study, a three-dimensional numerical analysis of the airflow passing through a QUIK vehicle and the effect of the cooling system's placement relative to the vehicle's grille in five different cases was conducted. The effect of non-uniform airflow distribution on related radiator parameters such as the Darcy number, particle diameter, and inertial term was examined. The results indicate that the optimal placement range of the vehicle's cooling system for appropriate cooling performance is very limited. Additionally, non-uniform air velocity distribution plays a significant role in the radiator pressure drop. The inertial term is more significant in non-uniform flow conditions. For larger Forchheimer numbers, the change in radiator pressure drop for uniform compared to non-uniform flow distributions is about 22%.
 

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This study investigates the effects of ozone gas injection on reducing exhaust emissions in internal combustion engines (ICEs). Ozone (O₃), a highly reactive oxidizing agent, has been widely utilized for air and water purification. Its ability to break down pollutants makes it a promising alternative or supplement to conventional catalytic converters, which require expensive materials and periodic recycling. In this research, ozone gas was generated using the corona discharge method and injected into the combustion system to evaluate its impact on carbon monoxide (CO) emissions. A low-power 12-volt compressor, capable of producing up to 10 bar pressure, was used to ensure proper injection. A five-gas analyzer was employed to measure emission changes before and after ozone injection. Results indicated an average CO reduction of 34–40% across seven tested vehicles, with the highest effectiveness observed at steady-state engine operation and moderate loads. Furthermore, an increase in lambda (λ) values suggested improved air-fuel combustion efficiency. Statistical analysis, including standard deviation (±0.005) and a 95% confidence interval, confirmed the reliability of these findings. The results demonstrate that ozone injection can serve as a cost-effective method to supplement traditional emission control technologies, potentially reducing reliance on catalytic converters.
 

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Electric Power Steering (EPS) systems are increasingly being integrated into modern vehicles, offering enhanced fuel efficiency and improved maneuverability. However, these systems are often subject to noise and disturbances, which can significantly impact steering precision and driver comfort. Addressing these challenges requires the implementation of robust control strategies capable of mitigating noise and disturbances in EPS systems. This paper explores advanced methods for achieving robust control in Electric Power Steering systems by reducing noise interference and countering external disturbances. Key techniques involve adaptive control algorithms and robust filtering mechanisms that maintain system stability and performance even under variable operating conditions. Experimental results demonstrate that these robust control approaches effectively minimize noise levels and disturbance impacts, leading to smoother steering response and greater reliability. This study underscores the critical role of robust control in enhancing the functionality and safety of Electric Power Steering systems while highlighting the intricate dynamics between noise, disturbances, and control system robustness in automotive applications.

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The main objective of this study is to investigate the vibrational behavior of the crankshaft mechanism of an IC engine operated on motoring mode as a function of the lubricant type, oil temperature. This attempt included instrumenting the engine block with accelerometers to measure horizontal and vertical vibration intensity and running the engine on an electromotor test rig in a specific test procedure namely strip-down method. The experiments were conducted with various cranktrain configurations under different engine speeds, lubricant types and oil temperatures. The results showed that vibration intensity of the cranktrain mechanism increases with increasing engine speed. This vibrations level was maximum in the highest speed. Changes in vertical vibrations caused by crankshaft in different conditions were almost similar to horizontal vibration changes. Also, the engine vibration caused by crankshaft were not affected by the oil type and oil temperature at all engine speeds, and increase in the speed had a very slight effect on this vibration. The engine vibrations due to reciprocating masses increased significantly with the speed rise, and altered by changes in oil temperature. Changing the oil type had almost no effect on vertical vibration caused by the movement of the reciprocating masses at any engine speed. But the horizontal vibration caused by them at a constant oil temperature increased by changing the oil type from 20w50 to 10w40. The experimental results showed that the contribution of the reciprocating masses from the vibrations caused by cranktrain mechanism was much higher than that of the crankshaft.
 

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This study develops and validates a simplified testing methodology aligned with UNECE Regulation No. 49 to quantify particle number (PN) emissions from diesel vehicles. A modified World Harmonized Vehicle Cycle (WHVC) was implemented, incorporating steady-state operational segments (urban: 21.3 km/h, rural: 43.6 km/h, motorway: 76.7 km/h), and applied to evaluate 51 Iranian-manufactured diesel vehicles. The tested fleet comprised heavy-duty trucks, buses, and pickup trucks equipped with diverse propulsion systems (e.g., ISF3.8s5154, OM457LA.IV) and after-treatment technologies, including SCR, DOC, and DPF. Results demonstrate that original equipment manufacturer (OEM)-installed DPFs reduced PN emissions by 7000-fold compared to non-DPF-equipped vehicles (2.49 × 10¹⁰ vs. 1.74 × 10¹⁴ particles/km; p < 0.001). Euro VI-compliant vehicles exhibited the lowest emissions (6.01 × 10¹⁰ particles/km), outperforming Euro V and Enhanced Environmentally Friendly Vehicle (EEV) standards. These findings underscore the necessity of adopting OEM-grade filtration systems and enforcing stringent emission regulations, such as Euro VI, to mitigate particulate pollution in urban environments. The methodology provides a replicable framework for emerging markets to align with global emission compliance protocols.
 

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Ensuring that ethically sound decisions are made under complex, real-world conditions is a central challenge in deploying autonomous vehicles (AVs). This paper introduces a human-centric risk mitigation framework using Deep Q-Networks (DQNs) and a specially designed reward function to minimize the likelihood of fatal injuries, passenger harm, and vehicle damage. The approach uses a comprehensive state representation that captures the AV’s dynamics and its surroundings (including the identification of vulnerable road users), and it explicitly prioritizes human safety in the decision-making process. The proposed DQN policy is evaluated in the CARLA simulator across three ethically challenging scenarios: a malfunctioning traffic signal, a cyclist’s sudden swerve, and a child running into the street. In these scenarios, the DQN-based policy consistently minimizes severe outcomes and prioritizes the protection of vulnerable road users, outperforming a conventional collision-avoidance strategy in terms of safety. These findings demonstrate the feasibility of deep reinforcement learning for ethically aligned decision-making in AVs and point toward a pathway for developing safer and more socially responsible autonomous transportation systems.